The syndrome known as regressive autism is a multifaceted disease entity that can present with a multitude of protean manifestations that has defied an accepted definitive etiology to date. Common to many or most of these associated disease states is a generalized decrement in behavior and communication skills. Previously this deficiency has been attributed to heavy metal intoxication, among other suspected pathobiologies. The current invention describes actual pathogenic compounds known as mycotoxins, formed by yeasts, fungi and molds that infect and cause disease in mammals and eukaryotes. For instance, the mycotoxin gliotoxin, produced by Candida, Aspergillus and Penicillium species, among others, has been shown to rapidly bind to sulfur containing molecules and render many molecules and proteins and enzymes nonfunctional. Gliotoxin has also been shown to bind to, deplete, and oxidize glutathione, a crucial antioxidant, causing oxidative stress. Glutathione is also responsible for the effective function of the crucial enzyme systems known as metallothioneins, which are needed for metabolism and maintenance of crucial metals in the brain and other bodily sites. Aflatoxin is similarly produced by mycotoxigenic fungal species and is immunosuppressive, inhibits protein synthesis and is carcinogenic, and may be a co-factor in many of the same disease states.